1. Field of the Invention
The present invention generally relates to pyrodetectors and more specifically to a method for manufacturing a pyrodetector apparatus.
2. Description of the Related Art
In the manufacture of integrated pyrodetector apparatus, individual pyrodetector elements are constructed on a substrate. Dependent on the employment, the pyrodetector apparatus encompasses four 256.times.256 or even more pyrodetector elements.
Substrates having low thermal conduction and low heat capacity are required for manufacturing integrated pyrodetectors to assure a sensitive response of the pyrodetector apparatus.
For constructing an integrated pyrodetector apparatus, it is known to employ a substrate of silicon whose surface is provided with a thin membrane of silicon oxide and silicon nitride. Proceeding from the back side, a depression is etched into the substrate within which the membrane of silicon oxide and silicon nitride is uncovered. The membrane spans the depression. The pyrodetector elements are constructed on the surface of the membrane. This method is not suitable for large-area pyrodetector apparatus because the membranes do not have the necessary mechanical stability. Another known method provides for constructing thin membranes at supporting points having a slight distance (approximately 1 .mu.m) from the substrate surface. The electrodes and pyro-active layer are then applied thereon. This method is known under the name of Surface-Micromachining (see, for example, D. L. Polla et al. , Appl. Phys. Lett. 59, pages 3539-3541 (1991)) .